var globalDepth = 15;

var _hackEngine = null;
var _evalEngine = null;
var _movePoller = null;

const STOCKFISH_PATH = "/bundles/app/js/vendor/jschessengine/stockfish.asm.1abfa10c.js";
const CHAR_MAP = { a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8 };

function startEngines(playerColour) {
  let baseFen = getBoardFen();
  let evalSideToMove = "w";
  let activeSide = "w";

  // --- Hack engine ---
  _hackEngine = new Worker(STOCKFISH_PATH);
  _hackEngine.postMessage(`position fen ${baseFen} ${playerColour}`);
  _hackEngine.postMessage("go wtime 300000 btime 300000 winc 2000 binc 2000");
  _hackEngine.postMessage(`go depth ${globalDepth}`);

  _hackEngine.onmessage = function(event) {
    if (!event.data.startsWith("bestmove")) return;

    const bestMove = event.data.split(" ")[1];
    const display = document.getElementById("best-move");
    if (display) display.textContent = `Best move: ${bestMove}  (depth ${globalDepth})`;

    document.querySelectorAll(".cheat-highlight").forEach(el => el.remove());

    const m = bestMove.split("");
    const from = `${CHAR_MAP[m[0]]}${m[1]}`;
    const to   = `${CHAR_MAP[m[2]]}${m[3]}`;
    const board = document.querySelector("wc-chess-board");
    if (!board) return;

    [from, to].forEach(sq => {
      const hl = document.createElement("div");
      hl.className = `highlight cheat-highlight square-${sq}`;
      hl.style = "background:red;opacity:0.5";
      board.appendChild(hl);
    });
  };

  // --- Eval engine ---
  _evalEngine = new Worker(STOCKFISH_PATH);
  let evalGeneration = 0;

  function startEvalSearch() {
    activeSide = evalSideToMove;
    const gen = ++evalGeneration;
    const side = activeSide;
    _evalEngine.postMessage("stop");
    _evalEngine.postMessage(`position fen ${baseFen} ${evalSideToMove}`);
    _evalEngine.postMessage("go depth 10");

    let pending = null;
    _evalEngine.onmessage = function(event) {
      if (gen !== evalGeneration) return; // discard stale results from old search
      if (event.data.startsWith("info")) {
        const scoreCP   = event.data.match(/score cp (-?\d+)/);
        const scoreMate = event.data.match(/score mate (-?\d+)/);
        if (scoreMate) pending = { val: parseInt(scoreMate[1]), isMate: true };
        else if (scoreCP) pending = { val: parseInt(scoreCP[1]), isMate: false };
      } else if (event.data.startsWith("bestmove") && pending) {
        // Only update the bar once the search is fully done — avoids wild swings
        // from shallow-depth lines (e.g. seeing a capture but not the recapture)
        updateEvalBar(pending.val, pending.isMate, side);
        pending = null;
      }
    };
  }
  startEvalSearch();

  // --- Move poller ---
  _movePoller = setInterval(() => {
    const newFen = getBoardFen();
    if (newFen === baseFen) return;
    baseFen = newFen;

    evalSideToMove = evalSideToMove === "w" ? "b" : "w";
    startEvalSearch();

    _hackEngine.postMessage(`position fen ${baseFen} ${playerColour}`);
    _hackEngine.postMessage("go wtime 300000 btime 300000 winc 2000 binc 2000");
    _hackEngine.postMessage(`go depth ${globalDepth}`);
  }, 500);
}

function stopEngines() {
  if (_movePoller)  { clearInterval(_movePoller);    _movePoller  = null; }
  if (_evalEngine)  { _evalEngine.terminate();        _evalEngine  = null; }
  if (_hackEngine)  { _hackEngine.terminate();        _hackEngine  = null; }
  document.querySelectorAll(".cheat-highlight").forEach(el => el.remove());
}